Generally, as communication and information processing technology are developed, the use of portable devices, such as mobile phones, that are convenient to carry is gradually increasing. With the development of technology, there is a trend in which new model terminals, the efficiency of which is improved, are being frequently popularized.
For the charging of such a portable device, a contact type charging scheme, or a non-contact charging scheme, which charges a battery using magnetic coupling without electrical contact, in order to solve the problems of the contact type charging scheme that result form the exposure of the contact terminals to the outside, is being used.
In relation to technology corresponding to such a non-contact charger, a scheme that performs charging by wireless communication between a battery pack and a charging device using a magnetic body core, such as unexamined Korean Pat. No. 2002-0035242 previously filed, entitled “Contactless Type Charging Device Of Storage Battery For Mobile Device Using Induction Coupling,” and a scheme that solves the problem of the magnetic body core using a transformer in which a wire is formed on a printed circuit substrate, such as previously filed unexamined Korean Pat. No. 2002-0057469, entitled “Coreless Ultra Thin Type Printed Circuit Substrate Transformer And Non-contact Battery Charger Using Printed Circuit Substrate Transformer,” have been proposed.
The present applicant proposed technology that constructs a wireless charging pad for performing a non-contact charging function, is configured such that the battery pack of a portable device is placed on the wireless charging pad for performing a non-contact charging function and, therefore, allows non-contact charging to be performed through “Wireless Charging Pad And Battery Pack Employing Radio Frequency Identification Technology (previously filed Korean Appl. No. 2004-48286).”
However, when detecting the portable device or the battery pack placed on the non-contact charging pad, the conventional technology depends on a scheme for transmitting Radio Frequency (RF) carrier signals to the outside through a reader antenna, and then detecting whether return signals exist, so that it is problematic in that the detection of the battery pack and the monitoring and controlling of the charging state through the detection are limitedly performed.
Furthermore, in the case in which a coin, a metal pen, a pair of scissors or the like (hereinafter referred to as a foreign object), other than the battery pack or the portable device, are placed on the non-contact charging pad, power transmission is continuously performed, so that a problem occurs in that the foreign object placed on the non-contact charging pad is heated by induction heating.
Furthermore, the non-contact charging pad only has a function of charging terminals or battery packs, so that a problem occurs in that the efficiency thereof is lowered.